This application claims the priority of German Application No. DE 100 55 768.6, filed Nov. 10, 2000, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an assembled vehicle brake disk having a basically rotationally symmetrical friction ring which is fastened by way of several linking points in a rigid or floating manner on a basically rotationally symmetrical hub part. With respect to the technical environment, reference is made, for example, to German Patent Document DE 195 28 434 A1.
Particularly with respect to light-weight construction aspects, brake disks are no longer produced in one piece but are assembled of a friction ring as well as a so-called hub part which may be constructed, for example, as on passenger car brake disks, in a conventionally pot-shaped manner. In DE 195 28 434 A1 only one example thereof is shown, in which, conventionally, not only the friction ring as well as the hub part represent basically rotationally symmetrical components but also so-called linking points, by way of which the friction ring is fastened to the hub part, are arranged in a symmetrically or uniformly distributed manner along the brake disk circumference. In this case, the present invention relates to many different types of linking points. That is, the problems described in the following as well as the invention are not limited to special constructions of linking points. Only several discrete linking points should be provided which fix the friction ring with respect to the hub part at least in the circumferential direction. In contrast, particularly in the axial direction, the friction ring can definitely be fastened in a floating manner on the hub part. Only as examples of possible constructions of the linking points, pin-shaped or screw-shaped connection elements should be mentioned here which are preferably aligned in the axial direction or radial direction of the brake disk. However, in addition, connections are mentioned which are produced by deforming, for example, lugs or the like.
A problem which constantly recurs basically on brakes (at least during their development) is the so-called brake squealing which, among other things, is significantly determined by the large number of natural frequencies and the type of natural oscillation forms of the entire vehicle braking system. It is therefore an object to keep the excitation of the natural frequencies or the natural oscillation forms of the individual brake disk components and of the entire system as low as possible in order to avoid undesirable noise radiations during a braking operation.
In principle, the xe2x80x9cloudspeakersxe2x80x9d or resonant bodies which are significant for the radiation of noise in a vehicle braking system are formed by the brake disks. As a result of their rotationally symmetrical construction, the natural oscillation forms develop here almost uniformly along the outer circumference. In the case of friction rings with a floating bearing, comparable situations may also occur for the partially free interior edge of the friction ring, which disadvantageously still intensifies the possibilities of generating noise.
It is an object of certain preferred embodiments of the present invention to indicate how brake squealing or undesirable noise radiations at a brake disk having a rotationally symmetrical friction ring which is fastened by way of a plurality of linking points, in a rigid or floating manner, to a basically rotationally symmetrical hub part, can be effectively prevented or at least kept as low as possible.
A solution to this problem, according to certain preferred embodiments of the invention, is characterized in that at least two distances, which follow one another in the circumferential direction, differ from one another between mutually adjacent linking points respectively. Advantageous further developments are contained in preferred embodiments.
It was found that the natural oscillation forms of a brake disk which exist as a result of the system can be interfered with by a targeted arrangement of the linking points with respect to their formation. That is, the linking points form so-called interference points or a difficulty with respect to the oscillation buildup in the brake disk. Since the natural oscillation forms of the disk viewed along its circumference can, in practice, develop only in a uniform manner, as a result of a non-uniform circumferential distribution of the above-mentioned linking points between the friction ring and the hub part, critical natural oscillation forms or natural frequencies of the assembled brake disk can even be eliminated. In this case, it may be sufficient for the non-uniform distribution of the linking points in the circumferential direction of the brake disk to be created such that, only in the case of three successive linking points, the distances will differ between two adjacent linking points respectively. For example, the first and second linking point enclose a sector angle of 20xc2x0, and the second and third linking point enclose a sector angle of, for example, 35xc2x0. However, it is also possible to arrange all linking points in their entirety to be non-uniformly distributed in the circumferential direction.
In this case, it is particularly advantageous for the total number of linking points to be uneven because the natural oscillations of the disk can form only in an even-numbered fashion. In this case, the absolute amount of the distance between the linking points and the number of linking points decide the frequency range which can be influenced thereby. Thus, a disk construction with a total of five linking points is interfered with with respect to its oscillation behavior at a clearly lower frequency than one which has, for example, nine linking points. Generally, a lower number of linking points per circumferential segment may therefore be provided with respect to lower-frequency noise radiations and a higher number may be provided with respect to higher-frequency noise radiations.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.